Tourniquet

An emergency measure to stop profuse bleeding. Used when direct pressure on the wound is not enough to slow the bleeding. No longer recommended by doctors, due to the fact that they have to amputate a large percentage of the limbs that have had a tourniquet applied. Let me repeat that:

No matter what you heard in a first aid course two decades ago, tourniquets are no longer recommended as a measure to stop bleeding.

Tourniquets areindicated to stop bleeding when the patient's life is in danger due to blood loss.

It is, however, not recommended to go wily-nilly applying tourniquets. Please let the professionals do it, if at all possible. This is one of the many reasons why everyone should take a beginner's first aid course.

Note:
I was a corpsman and 8404. In general, Superunknown_GP is correct, tourniquets are expected to cause the loss of the limb. This is, however, not a good reason to let someone die.